Calculators On-line - Here you can do all those conversions for problems like temperature and distance.
The Primes Page - Everything that you ever wanted to know about prime numbers.
On Roman Numerals - This page explains Roman numerals and has a handy box for converting from Roman to Arabic numerals or from Arabic to Roman.
The Mega Penny Project - Have you ever wondered how big a pile of ten billion pennies would be? Take a look at this site for piles of pennies from 16 pennies to one quintillion pennies.
Resources for Students
Mathematics
8/14/09